1. Field of the Invention
This invention relates to the field of energy conversion, and more particularly to a method and apparatus for converting the wave motion in a body of water to an alternative energy source such as electrical energy.
2. Brief Description of the Prior Art
There have been many attempts at harnessing the massive energy in the waves of the sea. However, such attempts have either made use of extremely complicated apparatuses, have used light weight float mechanisms to directly convert the up and down movement of the float into an alternate energy source thereby requiring a large number of floats and associated float mechanisms, or have been inadequate in the amount of energy produced to make the construction of the apparatus economically feasible.
One such prior art apparatus can be found in U.S. Pat. No. 4,145,885 to Solell. Solell describes a wave motor comprising a float, a displaceable member coupled to the float so as to be displaced by the ascent and descent of the float. A transmission is then operated directly by the movement of the float to rotate an output drive shaft which may be connected to an electrical generator, a pump, or any other device for utilizing or storing the mechanical energy produced by the wave motor.
Another U.S. Pat. No. 4,260,901 to Woodbridge shows a system for converting mechanical energy in the wave motion of a body of water into electrical energy, wherein a floatation element is buoyantly supported by the water and constrained to follow only the vertical component of the wave motion. The motion of the floatation element is transferred to an electrical generating device which produces electricity directly by the motion between a flux-producing device and the electrical coil of a generator. In Woodbridge, a cylindrical water column is utilized, but only to support the float which is not sealed relative to the cylindrical housing, but rather has a "clearance fit" within the internal void of the cylinder.
Another float/cylinder arrangement is shown in Vrana et al., U.S. Pat. No. 3,668,412. The Vrana et al. apparatus is based upon the principle of a large float which exerts force upwardly at a time of a risen tide and downwardly due to gravity at a time of a fallen tide, with the energy being converted to a rotatable horizontal shaft for driving an electrical generator while performing other useful work, the energy in the float being released at low tide after being stored from the rising of the float during the high tide condition.
The buoy motor of Weills, U.S. Pat. No. 2,871,790, also uses a buoy which moves upwardly and downwardly within cylindrical units as the waves move them upwardly and allow them to fall, providing waterfalls operable on a turbine connected to a generator for generating power through the operation of motors.
Donatelli, U.S. Pat. No. 3,746,875, teaches a power plant operable to generate electrical energy both from the up and down movement of the ocean's surface by means of a floatation platform slidably connected with a structure fixed to the ocean floor. Electricity is generated from a mechanism driven by the up and down movement of the platform and from other mechanisms in the form of paddle wheels driven by the flow of water directed across the platform.
Another wave-operated generator system which utilizes a flotation means for coupling the vertical movement of waves to an electrical generator is found in U.S. Pat. No. 4,392,060 to Ivy. Ivy shows a particular arrangement of a rack and pinion assembly for use as a transmission for converting the wave motion to mechanical energy in the form of a rotation of a shaft.
Other patents dealing with the subject of converting wave motion to electrical energy, but not as pertinent as those described specifically above, include the following U.S. Pat. Nos.: 4,476,396 to Calvert, Jr.; 3,697,764 to Spanziola, et al.; 3,898,471 to Schera, Jr.; 3,930,168 to Tornabene; 3,964,264 to Tornabene; 4,009,395 to Long et al.; 4,268,757 to Rogers; 4,281,257 to Testa et al.; 4,454,429 to Buonome; 4,490,621 to Watabe et al.; 4,560,884 to Whittecar; 4,622,473 to Curry; 4,599,858 to LaStella et al.; and 4,739,182 to Kanderi.
Several of the above-mentioned patents combine the output from a plurality of floatation means by some kind of a transmission device for each of the floatation means operating on a common output shaft. However, at any one floatation location, the amount of energy that is removable from the wave motion of the sea is solely dependent upon the size of the individual floatation means, and it is only through the transmission devices that the accumulation of energy is produced. It would be an improvement in such systems if the energy from a plurality of locations in the sea were to act on a single floatation means and if such system included a further plurality of such floatation means for producing substantially more energy output from the overall system.
Another deficiency of the prior art lies in the fact that each of the floatation means depends upon the buoyancy and weight of the float element itself. The larger and heavier the float element is, the greater the downward force for operating the electrical generator due to gravity acting on the float element. However, when a heavy float element is used, a great deal of energy is required by the ocean to buoy the heavy weighted float element upwardly. It would be a substantial improvement in the efficiency of the system if the weight of the water itself which causes the float element to rise is calculated in the total amount of energy that is obtainable by the system as the wave falls. That is, in prior art systems, the greatest captured energy occurs when the float element is being pushed up by the wave motion of the sea, but very little energy is captured when the floatation element falls of its own weight. The amount of energy due to the weight of the water dropping is thus wasted in such systems for all practical purposes.